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1. Field of the Invention
The present invention relates to a hand fin to aid in swimming, and more particularly to an aerodynamically shaped hand fin, formed by two air foils sharing an adjacent surface with both having a leading edge depending from the leading edge of the adjacent surface of the two air foils to a trailing edge, with the distal ends forming a tip joining the leading and trailing edges, and a hand interface.
The present invention adapts a combination of a fish""s caudal fin (the tail fin) and a whale""s fluke (the tail fin) propulsion systems into a useful structure that is ergonomically designed for use by human hands in swimming. This invention also discloses a wrist strap, a securing string, a glove, or a combination of both to aid in the use of hand fins for swimming. This invention also describes alternate embodiments of this hand fin that have additional advantages.
2. Background of the Invention
In the past, swimming under water with swim fins designed for the feet has made the use of the hands impractical, difficult, and inefficient. The problem with using the hands arises from the increased speed produced from using swim fins designed for the feet. At present, hands or hands wearing webbed gloves or hands wearing paddles function only as paddles in the water. The speed at which a person is swimming greatly influences the efficiency and possible use of a paddle. A similar example is seen when trying to use paddles with a boat that has a motor (the motor is similar to using foot fins). When the boat is not using the motor, the paddles can pull the boat through the water. When the boat is using a motor for propulsion, the paddles are useless.
Paddles are a form of xe2x80x9cdrag propulsion.xe2x80x9d This means they create a void in the water as they pull through the water. The water surrounding the paddle flows into the void and pulls the paddle (and person in the boat) in the direction of the void. If the motor powers the boat more quickly through the water, the paddles cannot create a void where the water moving into the void moves faster than the boat. The water flowing into the void is slower and provides no propulsion. If anything, the paddles would probably inhibit the flow of the boat through the water by causing drag. The same kind of situation arises with the use of the hands in swimming underwater while using swim fins on the feet. The hands cause more xe2x80x9cdragxe2x80x9d than any benefit generated from their use as a paddle. Thus, when swimming underwater with swim fins on the feet, the hands are almost never used.
This invention affects the ability of the hands to be used in swimming with swim fins on the feet. By using ergonomically designed xe2x80x9cdual air foil tapering wing shapedxe2x80x9d hand fins for use with human hands in swimming, propulsion can be produced by the xe2x80x9cliftxe2x80x9d that these xe2x80x9cwing-shapedxe2x80x9d hand fins create by moving them through the water at a correct angle of attack. One type of xe2x80x9cdual air foil tapering wing shapedxe2x80x9d fins are found in the symmetrical tail shape (fluke) used by dolphins and whales to produce extremely efficient and powerful thrust in water. The xe2x80x9cliftxe2x80x9d produced by a large whale using a tail fin is enough to propel a forty-five ton whale twenty feet above the water. Asymmetrical dual wing shapes are also found on many of the best swimming sharks and other fishes. This patent discloses both types of fin strategies for use with the hands in swimming.
This xe2x80x9cliftxe2x80x9d is the same type of force created by the wings of an airplane (these hand fins are also lifting forms). These hand fins are somewhat different than airplane wings in that they are curved to the center and rear of the form to produce a concentration of the flowing water into the center of the hand fin. This creates a water current that helps to give additional thrust to the hand fin and pulls water from the sides which decreases vortices and drag when these shapes are moved through the water. These hand fins, when moved horizontally in the water, xe2x80x9csailxe2x80x9d across a body of water much as a glider sails through the air. This gliding motion is caused by xe2x80x9clift.xe2x80x9d A great advantage of using lift is that lift increases with the speed of the flowing water.
Even though the forces of lift are increased with an increase in the speed of water flowing over the surface, the effort needed to create a proper angle of attack and movement through water is the same or decreases. This makes this hand fin invention exceptionally useful for swimming with hand swimming fins for the feet because they increase the speed that the swimmer moves through the water. These hand fins use this increased water speed to give additional lift and propulsion to the swimmer with little or no effort required to achieve this increased propulsion. There are a number of articles dealing with the science of this issue that have issued within the last few years. Many of the articles written by Professor Walker at the University of Southern Maine deal with the efficiencies of rowing (the use of paddles for propulsion) versus xe2x80x9cflappingxe2x80x9d (the use of airfoils for propulsion) in water. In these articles, the conclusion was that the proper use of airfoils was always more efficient than using paddles at every speed and at all normal Reynolds numbers (RE). The most relevant sites on the web are listed below: http://www.usm.maine.edu/xcx9cwalker/pdfs/SICB2002 ms.pdf (Rowing and Flapping at Low Rexe2x80x94Jeffrey A. Walkerxe2x80x94American Zoologist, in press) http://www.usm.maine.edu/xcx9cwalker/pdfs/JEB2002.pdf [The Journal of Experimental Biology 205, 177-187 (2002)-Printed in Great Britain(copyright) The Company of Biologists Limited 2002-JEB3576] http://www.usm.maine.edu/xcx9cwalker/pdfs/ProcRoySocB2000.pdf (Mechanical performance of aquatic rowing and flyingxe2x80x94Jeffrey A. Walker* and Mark W. Westneatxe2x80x94Royal Societyxe2x80x94doi 10.1098/rspb.2000.1224) http://mshades.free.fr/flapping/flapping.html (The image describes the OPTIMAL FLAPPING WING CYCLE (with best propulsive efficiency), and below, the cycle of a caudal (movement of a dolphin flipper),) http://mshades.free.fr/flapping/flipper.html (bionic analysis: MOVEMENT OF A DOLPHIN FLIPPERxe2x86x92PROPULSIVE HYDROFOIL)
U.S. Pat. No. 6,375,531 teaches the principle of using a lifting xe2x80x9ctail finxe2x80x9d from a foot fin for swimming with the hand. Although many of the principles are the same, the U.S. Pat. No. 6,375,531 does not teach an ergonomic hand interface for the swimmer. Not having an ergonomic interface for the hand of the swimmer causes numerous problems. This patent reveals the use of ergonomic hand interfaces.
An example of this principle is seen everyday on airplanes. The motor and propeller can move a structure through the air, but the lifting forms designed into the wings increase the efficiency, speed, and control of the flying structure much as these hand fins help swimmers.
A secondary advantage of using these hand fins arises from the increased ability of the swimmer to change direction easily and have more control while swimming. Because these hand fins aid in propulsion, they can be used to help alter direction without losing speed or increasing effort. By simply aiming them in the desired direction and using them normally, the swimmer is propelled in the new direction without a loss of speed or increase in effort. These hand fins can also be used as rudders for steering. They make swimming a more aquatic experience for the swimmer because he is able to use all of his limbs while swimming and control his direction of swimming with great ease.
When swimming in natural bodies of water, situations occur where turning around is difficult or impossible. These fins can be held in front of the swimmer and can be used to propel the swimmer backwards away from possible danger or undesirable creatures without requiring the swimmer to turn around. Another advantage of being able to swim backwards is that one can move away from danger while continuing to monitor the cause of the danger by facing it.
In an exemplary embodiment of the invention, a hand-held hand fin apparatus includes a leading edge having a first thickness, a trailing edge having a second thickness, narrower than the first thickness, and a main body portion extending between the leading edge and the trailing edge. The main body portion is shaped such that water flowing over the main body portion is guided toward a center of the swimming fin. Preferably, the leading edge, trailing edge and main body portion define a fishtail-shaped hand swimming fin, wherein a cross-section of the fishtail-shaped hand swimming fin is aerodynamically shaped to generate lift.
The hand swimming fin may further include a handle portion that is shaped to be grasped by a human hand. In one arrangement, the handle portion is defined by an opening in the main body of the hand fin apparatus. A handle pad is selectively attachable to the handle portion for adjusting a grip size of the handle.
The main body portion preferably has a third thickness that is larger than the first thickness, and tapers towards the trailing edge direction. A focusing raceway may be formed along the center of the symmetrical hand fin apparatus. The focusing raceway extends between the main body portion and the trailing wedge portion, tapering in thickness toward the center of the hand fin apparatus. The leading edge and trailing edge join at two trailing points at opposite distal ends of the hand fin apparatus.
The hand swimming fin may also include a strap attachable to the handle portion of the hand fin apparatus. The strap may include a means for releasably securing the strap to the hand fin apparatus, and for securing a user""s hand to the hand swimming fin. In one arrangement, the hand fin apparatus is inflatable. In an alternate embodiment, the hand fin apparatus is hollow, with a chamber located within the hand fin apparatus. The hand fin apparatus may also be of solid construction, with different material used to provide a flexible tail fin portion.
Preferably, the hand fin apparatus is substantially symmetrical from top to bottom, and side to side. The hand fin apparatus includes a main body having an aerodynamic-shaped cross-section, with a leading edge and a trailing edge. A contour of the main body is shaped such that water flowing over the main body is guided toward a center of the hand fin apparatus. The hand fin also includes a handle portion that is shaped to be grasped by a human hand.
In yet another exemplary embodiment of the invention, the hand fin apparatus may be manufactured with a leading edge material; a main body portion secured to the leading edge material, the main body portion less rigid than the leading edge material; and a flexible trailing edge material secured to the main body portion. The flexible trailing edge material is less rigid than the main body portion.